Diverse subterranean fungi of an underground iron ore mine

Abstract

Mines and caves are unusual ecosystems containing unique fungi and are greatly understudied compared to other environments. The Soudan Mine in Tower, MN, an iron ore mine that closed in 1963 after operating for 80 years, was sampled to explore fungal diversity and to investigate taxa that tolerate heavy metals for potential bioprocessing technologies or as sources of bioactive molecules for drug discovery and possible biocontrol for white-nose syndrome (WNS) of bats. The mine is 714 m deep, has 18 levels and contains large quantities of wooden timbers, in contrast to many other oligotrophic subterranean environments. Fungi were cultured from samples and the ITS region was sequenced for identification and phylogenetic analysis. Results show Ascomycota are the dominant fungi followed by Basidiomycota and Mucoromycota. Out of 164 identified taxa, 108 belong to the Ascomycota and 26 and 31 to Basidiomycota and Mucoromycota, respectively. There are also 46 taxa that do not match (<97% BLAST GenBank identity) sequenced fungal species. Examples of the most commonly isolated Ascomycota include Scytalidium sp., Mariannaea comptospora, Hypocrea pachybasidioides, Oidiodendron griseum and Pochonia bulbillosa; Basidiomycota include Postia sp., Sistotrema brinkmannii, Calocera sp., Amylocorticiellum sp.; Mucoromycota include Mortierella parvispora, M. gamsii, M. hyaline, M. basiparvispora and Mortierella sp. Unusual growth forms were also found including large quantities of black rhizomorphs of Armillaria sinapina and white mycelial cords of Postia sp. mycelium, as well as Pseudogymnoascus species growing over large areas of mine walls and ceiling. The mine environment is a relatively extreme environment for fungi, with the presence of high levels of heavy metals, complete darkness and poor nutrient availability. Several genera are similar to those isolated in other extreme environments but phylogenetic analyses show differences in species between these environments. Results indicate this subterranean environment hosts a wide diversity of fungi, many of them not found in above ground environments.

Living in the dark: Bat caves as hotspots of fungal diversity

“…Subsequently, other studies added more fungal taxa to that list, increasing the number of fungi found in caves [e.g. 11 , 15 – 18 , 20 – 27 , 64 , 71 , 80 , 81 ]. In two karst caves in China, Zhang et al [ 16 ] reported that 28 (24%) of the 116 genera and 111 (59%) of the 188 identified species were reported for the first time in cave environments.…”

Rock Surface Fungi in Deep Continental Biosphere—Exploration of Microbial Community Formation with Subsurface In Situ Biofilm Trap

“…Mortierella sp. have been found from different hostile environments including hydrocarbon contaminated soils and heavy metal rich underground iron ore mines [ 87 , 88 ]. They have been shown to produce nitrous oxide (N 2 O), and host Burkholderia -related endosymbiotic bacteria [ 89 ].…”

Characterization of Martelella soudanensis sp. nov., Isolated from a Mine Sediment

“…However, there were some differences in the respective compositions of some long-chain fatty acids, such as C18:1 ω5c, C19:0 iso, and C20:1 ω7c. The respiratory quinones of strains NC18 T and NC20 were Q-10, typical for the genus Martelella [ 1 , 2 , 3 , 4 , 5 , 6 ].…”

“…The mine reaches a depth of 714 m below the surface, providing access to deep subsurface brines entrained in a massive hematite formation [ 3 , 4 ]. Previous cultivation-based and metagenomics studies reported the presence of diverse microbial communities, including the iron-oxidizing Marinobacter and iron-reducing Desulfuromonas in a calcium- and sodium-rich brine that reaches salinities as high as 4.2% ( w / v ) from these boreholes [ 3 , 5 , 6 ].…”